Sync from Google Sheet to Google Calender stopped working

I have a scenario that syncs a google sheet with a google calendar to create events on the calendar. First it deletes all events on the calendar using a “Delete an Event” module and then recreates them all in order to include anything that might have been added to the sheet. The sync runs every 2 hours from 9 am - 10:00 pm. Last month it worked great and then at some point started throwing the error:

“Missing value of required parameter ‘event’.”

Make support said this tells us that the calendar appears to not have any events in it - but it does! They could not figure out what the problem was and told me to create a new calendar - which I did - which fixed the problem - but now it started throwing the error again.

Does anyone have any idea what might be wrong or what I need to do about it?

Thanks
Tom